1. Field of the Invention
The present invention relates to an image pick-up device and, more particularly, to a suitable image pick-up device for performing adjustment of an optical system, such as an automatic-focussing control or the like, in accordance with a plurality of television systems, such as NTSC system or PAL system.
2. Related Background Art
Up to this time, there have been many television systems in the world, as represented by the NTSC system and the PAL system, which have been used in different localities respectively. In addition to these systems, each nation has approached to propose a further highly accurate HDTV standard, make it on an experimental basis and investigate its realization in recent years. The respective systems are different in space frequency characteristic with respect to video signals or the like from each other, for example, the NTSC system and the PAL system respectively have characteristics as shown in FIG. 22.
On the other hand, with an automatic-focussing system in a video camera for domestic use, a so-called TVAF (television automatic-focussing) system is now the main current, in which the focussing control is performed by determining as to whether or not the video signal is in focus based upon increase and decrease of higher harmonic elements in video signals to be projected.
However, in the structure of such a video camera compatible with some types of multiple television systems, when performing the focussing control by the TVAF system mentioned above, adjustments are required to optimize respective parameters every picture taking mode (standard: television system) for the reason that the respective television systems are different in space frequency. Accordingly, there has been a problem that the whole configuration was complicated.
In consideration of such a point as background, the primary object of the present invention is to provide an image pick-up device enabling to perform adjustment of an optical system suitably with a simple structure.
Also, the second object of the present invention is to provide an image pick-up device enabling to perform an optimum focussing adjustment as usual irrespective of the television systems.
In order to achieve the above-mentioned objects, according to a preferred embodiment of the present invention, there is provided an image pick-up device including an optical system for forming an optical image of an object to be projected, a photoelectric conversion means for outputting the optical image formed in the optical system as a video signal by photoelectric conversion, a conversion means into the video signals converting the image pick-up signal output from the photoelectric conversion means into the video signals in accordance with a plurality of signal standards, and an adjustment means for adjusting the optical system based upon the optical signal in accordance with the signal standard before conversion in the conversion means.
The above-mentioned objects can be attained, according to another preferred embodiment of the present invention, by an image pick-up device including an optical system for forming an optical image of an object to be projected, a photoelectric conversion means for outputting the optical image formed in the optical system as a video signal by photoelectric conversion, a storage means for storing the video signal output from the photoelectric conversion means so as to perform an image processing, and an adjustment means for adjusting the optical system based upon the video signal before store in the storage means.
The foregoing objects are accomplished, according to still another preferred embodiment of the present invention, with an image pick-up device including an optical system for forming an optical image of an object to be projected, a photoelectric conversion means for outputting the optical image formed in the optical system as a video signal by photoelectric conversion, a change means for changing a space frequency characteristic of the video signal output from the photoelectric conversion means so as to perform an image processing, and an adjustment means for adjusting the optical system based upon the video signal before change in space frequency characteristic in the change means.
Another object of the present invention is to provide an image pick-up device enabling to obtain the highest AF (auto-focus) characteristic as usual by performing adjustment of an optical system, such as an AF control or the like, based upon a video signal in accordance with a signal standard before conversion by a conversion means for converting the television system, for example, in accordance with a highly accurate HDTV standard.
In such an object of the present invention, although, when performing the AF control or the like by use of a video signal from which high frequency elements have been removed by the conversion processing in the conversion means, it is required to have a complicated structure so as to optimize respective parameters every picture taking mode (television system: signal standard), the AF control or the like can be suitably performed with such a simple structure as a video signal including high frequency elements before conversion by the conversion means is used as it is.
Another object of the present invention is to prevent such inconvenience, as response characteristic in the FA system or the like is deteriorated by delay of video signals in a storage means i.e., the response is delayed or the control becomes unstable by hunting, by performing adjustment of an optical system based upon a video signal before store in the storage means such as an image memory or the like.
An additional object of the present invention is to enable to perform adjustment of an optical system suitably with a simple structure in which a video signal before store in a storage means such as an image memory or the like is used as it is.
Another object of the present invention is to perform adjustment of an optical system, such as an AF control or the like, based upon a video signal before change in space frequency characteristic in a change means, for example, a signal including a wide frequency band in accordance with an HDTV standard or the like. That is, although, when performing the AF control or the like by use of the video signal after change in space frequency characteristic in the change means, it is required to have a complicated structure so as to optimize respective parameters every picture taking mode (television system: signal standard), the AF control or the like can be suitably performed with such a simple structure as the video signal including a wide frequency band before change in space frequency characteristic in the change means is used as it is.